Peritumoural adipose tissue promotes ferroptosis resistance by 3-hydroxykynurenine-mediated suppression of ferritinophagy.

The peritumoural adipose tissue (PAT) is a key contributor to cancer therapy resistance, yet its role in regulating ferroptosis remains unclear. Here we demonstrate that PAT confers ferroptosis resistance to cancer cells by upregulating ferritin (FTH1/FTL) and sequestering intracellular iron. PAT-derived kynurenine (KYN) was identified as the principal mediator. KYN is taken up by cancer cells and metabolized to 3-hydroxykynurenine, which directly binds to nuclear receptor coactivator 4 (NCOA4). This interaction inhibits NCOA4-mediated ferritinophagy, preventing ferritin degradation and limiting the free iron pool required for ferroptosis. In murine models, pharmacological inhibition of the KYN pathway synergized with PD-1 blockade to overcome ferroptosis resistance and suppress tumour progression. These findings reveal a PAT-KYN-ferritinophagy axis that promotes ferroptosis resistance, highlighting the potential of targeting adipose-tumour cross-talk to enhance immunotherapy in PAT-associated tumours.